ENS 45518
ENS Event | |
|---|---|
16:05 Oct 19, 2009 | |
| Title | Automatic Closure of Primary Containment Isolation Valves Due to Invalid Signal |
| Event Description | On Monday, October 19, 2009, Limerick Unit 1 was operating at 100% power. At 1105 hours0.0128 days <br />0.307 hours <br />0.00183 weeks <br />4.204525e-4 months <br />, an invalid actuation of the 1B Reactor Enclosure Ventilation Exhaust Radiation Monitor occurred. The actuation caused a Division 2 Group 6C isolation signal, which caused primary containment isolation valves (PCIVs) to automatically close on the Containment Leak Detector Radiation Monitor (10-S182) and the Drywell Hydrogen/Oxygen Analyzer (10-S205). The 1A, 1C, and 1D channels were unaffected and indicated normal ventilation exhaust radiation levels during the event.
The cause of the event was a failure of a fuse holder in the 1B Reactor Enclosure Ventilation Exhaust Radiation Monitor. The radiation monitor is designed to fail-safe on a loss of power. The automatic closure of the PCIVs placed them in their fail-safe position. The failed fuse holder has been replaced and the radiation monitor was declared operable on Tuesday, October 20, 2009 at 1348 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.12914e-4 months <br />. The portion of the primary containment isolation system that received an actuation signal functioned successfully. All of the affected open isolation valves automatically closed. The only equipment malfunction during the event was the failed fuse holder. The Division 2 Group 6C isolation was a partial actuation. This event is reportable per 10CFR50.73(a)(2)(iv)(A) since isolation valves for the Containment Leak Detector Radiation Monitor and Drywell Hydrogen/Oxygen Analyzer automatically closed due to an invalid signal. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Limerick  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+861.23 h35.885 days <br />5.126 weeks <br />1.18 months <br />) | |
| Opened: | Jean Broillet 14:19 Nov 24, 2009 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Nov 24, 2009 |
| 45518 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 564642023-02-16T12:05:00016 February 2023 12:05:00
[Table view]Other Unspec Reqmnt, 10 CFR 50.73(a)(1), Submit an LER 60 Day Notification for an Invalid Actuation of the Emergency Service Water System ENS 562832022-11-02T23:29:0002 November 2022 23:29:00 10 CFR 50.73(a)(1), Submit an LER 60-DAY Telephonic Notification - Invalid Specific System Actuation ENS 553452021-05-13T11:00:00013 May 2021 11:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Containment Isolation Signal ENS 540832019-04-18T06:49:00018 April 2019 06:49:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a Unit 2 Containment Isolation Logic Due to a Blown Fuse ENS 540142019-02-22T15:30:00022 February 2019 15:30:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of a Unit 1 Containment Isolation Logic Due to a Blown Fuse ENS 519522016-03-28T05:50:00028 March 2016 05:50:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Inboard Isolation Logic ENS 485752012-10-13T23:41:00013 October 2012 23:41:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Multiple System Actuations ENS 468832011-04-02T16:18:0002 April 2011 16:18:00 10 CFR 50.73(a)(1), Submit an LER Loss of Rps/Ups Power Supply ENS 459622010-04-03T01:56:0003 April 2010 01:56:00 10 CFR 50.73(a)(1), Submit an LER Overvoltage Condition Causes Reactor Protective System Actuation ENS 455182009-10-19T16:05:00019 October 2009 16:05:00 10 CFR 50.73(a)(1), Submit an LER Automatic Closure of Primary Containment Isolation Valves Due to Invalid Signal ENS 442602008-04-09T08:16:0009 April 2008 08:16:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Notification for Invalid Specified System Actuation ENS 433662007-03-19T06:20:00019 March 2007 06:20:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuations During Testing ENS 428302006-07-09T22:49:0009 July 2006 22:49:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of the B Esw Pump ENS 425722006-03-14T21:40:00014 March 2006 21:40:00 10 CFR 50.73(a)(1), Submit an LER Inadvertant Core Spray Pump Actuation ENS 416672005-03-06T19:07:0006 March 2005 19:07:00 10 CFR 50.73(a)(1), Submit an LER Invalid Safety System Actuation During an Outage ENS 408952004-05-26T20:22:00026 May 2004 20:22:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Invalid Automatic Actuation Report: Containment Isoaltion Valves in More than One System 2023-02-16T12:05:00 | |